What would the next giant giant look like in California’s infamous San Andreas’ fault?
This is a repetition of 1857, when the earthquake was estimated to be between 7.7 and 7.9, which caused the faults in Monterey County to pass through Los Angeles County? Will it be more similar to the 1906 San Francisco earthquake that began offshore in the city and broke in two directions towards Humboldt and Santa Cruz counties?
Don’t bet on the same sequel.
That’s what a study published Monday in the Proceedings of the National Academy of Sciences’ papers. The report, co-written by scientists from Caltech in Pasadena, examines a massive earthquake that broke down in the Southeast Asian country of Myanmar on March 28, a similar fault to San Andreas.
Given the seismology in the region, the faults that eventually ruptured by the earthquake are much longer than scientists expected.
The implication of this study is that “the earthquake will never come back in the exact same way again.”
A local man drove past a damaged building after an earthquake in Naypyidaw, Myanmar on March 30.
(Aung Shine OO / Associated Press)
“It’s surprising that you can have such a long rupture,” said Jean-Philippe Avouac, a professor of geology, machinery and civil engineering at Caltech, co-author of the study.
The March Mandalay earthquake destroyed Myanmar, killing at least 3,791 people in Thailand and 63 others killed. High-rise buildings suffered losses from Ho Chi Minh City, Vietnam, and houses in the Ruri area of China were damaged. The loss is estimated at $1.9 billion, according to the U.S. Geological Survey.
This is the most powerful earthquake in Myanmar for at least 79 years.
“Violence” and “Extreme” shake red in the 7.7-magnitude earthquake in March.
(USGS)
The 7.7-magnitude earthquake ruptured an astonishing 317 miles, a discovery based on Antoine’s analysis of satellite data showing the movement of the Earth after the earthquake. That was the longest earthquake rupture ever.
By comparison, the 1906 earthquake in California ruptured 296 miles of the San Andreas fault. and the 1857 earthquake, 225 miles. Only longer earthquake ruptures were found in subductions deep in the sea.
It is clear from the study that while California’s next “big one” may have some characteristics of a previously recorded devastating earthquake, it is impossible to be an exact replay. As recent experiences in Myanmar have shown, even well-documented shortcomings can act in surprising ways.
The next step is to develop a model to simulate thousands of years of San Andreas failure to make an earthquake for this in the future. But San Andreas’ fault is “much more complicated.” “This won’t come anytime soon, because it’s a heavy calculation.”
Nevertheless, such simulations will provide “models of all possible scenarios so that we can better understand the series of breakages that may occur.”
Rescuers work on site at a high-rise building under construction in Bangkok, Thailand, which collapsed after a magnitude 7.7 earthquake centered on Myanmar on March 28.
(Wason Wanichakorn/AP)
For example, perhaps the faults in San Andreas would break in smaller, independent earthquakes.
Or it could be a bigger earthquake—not only the fault breaking from Monterrey to Los Angeles County, but maybe all the way to San Bernardino, Riverside and Empire counties, which could be over 8 magnitude. This geology will be the biggest simultaneous disaster in modern California history and suffered a huge state of suffering from the powerful Seismic shake sherake sherake sh.
By contrast, the footprint of the Northridge earthquake in 1994 was relatively limited, seriously affecting part of Los Angeles County, especially the San Fernando Valley, which is related to its relatively small magnitude of 6.7.
But while modeling previous activities on the San Andreas fault will provide a glimpse of possible results, it will not accurately determine that the next major earthquake will erupt.
“We can’t just expect the exact same thing to happen,” Antoine said. “It’s a question, just showing what the possible situations, the diversity of the scenarios and what the consequences of seeing each situation are.”
A Buddhist monk walked near the collapsed pagoda on March 30 after an earthquake occurred in central Myanmar.
(Thein Zaw/AP)
Sometimes, Avouac said, “For a long time, it was quiet and nothing happened…the pressure was getting worse, the fault locked in for a long time, nothing happened, and then, boom, you have a big earthquake.”
“And then you have other periods, during which you have a lot of [seismic] Activity, but these earthquakes are smaller. ” Avouac said.
But, in the researchers’ minds, the “small” earthquake is still very large for laymen. In the simulations studied, earthquakes of approximately 7.7 are common in certain periods. In other periods, earthquakes were maximized at an amplitude of around 7.5, but more frequently.
The entire length of the tactile fault – including areas that did not break during the March earthquake – from the Himalayas to the Andaman Sea, 750 miles north to the south, helping to adapt to the northward push of the Indian tectonic plate.
The fact that the 317-mile Sagan fault broke in March surprised scientists. In the last rupture in 1839, only about 170 miles of earthquake remained.
(Solene Antoine / Caltech)
Scientists call these “seismic gaps” “seismic gaps,” a specific area that has not been ruptured recently.
Typically, scientists would only expect the 170-mile-long tactile fault to rupture. These include a 100-mile extension that broke in the great earthquake in 1929 and 1930, and a 50-mile extension of a pair of serworms in 1946 and 1956.
Instead, even these fault segments broke down in a large marching earthquake.
Then what to give?
One possible explanation is the extraordinary smoothness of Sagaing failure. “People observed that when the fault is very stable, the rupture … tends to propagate at speed,” Avouac said.
The study also published results from computer model simulations examining how earthquakes would rupture along a portion of the entire 750-mile-long tactile fault. The code was developed by study co-author Kyungjae IM at Caltech, indicating that there will be no repeatable patterns over the hypothetical 1,400-year period.
In other words, the earthquake does not appear to reproduce like a clockwork, breaking the same fault in a repeatable predictable pattern.
“There is complexity here. This is because every time an earthquake occurs, the pressure of the fault is redistributed, which will affect the next earthquake.” “There is a self-induced complexity in the process, which leads to some randomness.”
There is a sure person, which will inevitably disappoint anyone who hopes that “big guys” will never attack California again.
“At some point there will be an earthquake,” Antoine said. “If the stress is increased on the fault, the fault will never exist forever.”
Further research and observations are crucial to refine models of possible future earthquakes, including outpost satellites operated by the European Space Agency, the authors said.
Another co-author of the study was Rajani Shrestha and Chris Milliner of Galt Technology. Chris Rollins of Earth Sciences in New Zealand; Kang Wang of Washington-based Earthscope Alliance; and Kejie Chen of Shenzhen Southern University of Science and Technology, China.
